Plunger pump

ABSTRACT

A plunger pump includes: a motor; a bracket attached to the motor; a holding member fixed to the bracket; a plunger extending in a axial direction; a pump head holding the plunger such that the plunger is capable of rotating and reciprocating in the axial direction; and a joint mechanism for converting rotation of the motor into rotation and reciprocation of the plunger, wherein the holding member includes first and second plate members each formed into a flat plate shape, and the first and second plate members are parallel to each other so as to sandwich the pump head.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2019-200948, filed on Nov. 5, 2019, the entire contents of which are incorporated herein by reference.

BACKGROUND (i) Technical Field

The present disclosure relates to a plunger pump.

(ii) Related Art

Japanese Unexamined Patent Application Publication No. 2017-137780 describes a plunger pump including a front frame to which a pump head is fixed.

SUMMARY

According to an aspect of the present disclosure, there is provided a plunger pump including: a motor; a bracket attached to the motor; a holding member fixed to the bracket; a plunger extending in a axial direction; a pump head holding the plunger such that the plunger is capable of rotating and reciprocating in the axial direction; and a joint mechanism for converting rotation of the motor into rotation and reciprocation of the plunger, wherein the holding member includes first and second plate members each formed into a flat plate shape, and the first and second plate members are parallel to each other so as to sandwich the pump head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of a plunger pump;

FIG. 2 is an external view of the plunger pump;

FIG. 3 is an external view of the plunger pump;

FIG. 4 is a cross-sectional view taken along A-A line of FIG. 3; and

FIG. 5 is a view of only the plate members.

DETAILED DESCRIPTION

FIGS. 1 to 3 are external views of a plunger pump 1. FIG. 4 is a cross-sectional view taken along A-A line of FIG. 3. The plunger pump 1 includes a motor 10, a bracket 20, plate members 30, a joint mechanism 40, a plunger 50, a nut 60, and a pump head 70. The bracket 20 is fixed to an outer surface of the motor 10 from which a rotational shaft 12 thereof protrudes. The bracket 20 includes: a fixed plate portion 22 fixed to the outer surface of the motor 10; and two connecting wall portions 24 protruding from the fixed plate portion 22 toward a distal end side of the rotational shaft 12 of the motor 10 and parallel to each other. Proximal end portions of the two plate members 30 are respectively fixed to the two connecting wall portions 24. The pump head 70 is sandwiched and held by distal ends of the two connecting wall portions 24.

The plate member 30 is fixed to the connecting wall portion 24 so as to adjust an angular position of the plate member 30 with respect to the connecting wall portion 24. Specifically, the plate member 30 is fixed to overlap the connecting wall portion 24 by Hexagon Socket Head Cap Screws (hereinafter referred to as screw bolts) B1 and B2. A receiving hole 25 formed in the connecting wall portion 24 through which the screw bolt B1 penetrates is formed into an arc shape. A center of this arc shape is a screw hole, formed in the connecting wall portion 24, through which the screw bolt B2 penetrates. On the other hand, the plate member 30 is formed with screw holes 35 and 36 screwed with the screw bolts B1 and B2, respectively. The screw bolt B1 is capable of fixing the plate member 30 at any angular position within the arc-shaped receiving hole 25. Thus, the plate member 30 is fixed to the connecting wall portion 24 at an adjustable angular position in a range of the receiving hole 25 about the screw bolt B2.

As illustrated in FIG. 4, the joint mechanism 40 is fixed to the distal end of the rotational shaft 12 protruding from the motor 10. The joint mechanism 40 connects the distal end of the rotational shaft 12 and a proximal end of the plunger 50 such that the rotational motion of the rotational shaft 12 is converted into the rotational motion of the plunger 50 and the reciprocating linear motion of the plunger 50 in the axial direction. The plunger 50 performs a reciprocating linear motion while rotating. Specifically, the joint mechanism 40 includes a spherical bearing 41, a pin 42, and a sleeve 43. The spherical bearing 41 holds a proximal end of the pin 42 such that the pin 42 pivots on the proximal end thereof. A distal end of the pin 42 is connected to the proximal end of the plunger 50 via the sleeve 43. When the joint mechanism 40 rotates, the spherical bearing 41 revolves around an axis of the rotational shaft 12, and the pin 42 pivots. In response to this, the plunger 50 linearly reciprocates while rotating, because an axial direction of the plunger 50 is inclined with respect to the axial direction of the rotational shaft 12. The spherical bearing 41, the pin 42, and the sleeve 43 are made of, but not limited to, metal. The plunger 50 only rotates, in such a posture that the axial direction of the rotational shaft 12 is the same as the axial direction of the plunger 50. The plunger 50 is made of, for example, but not limited to, ceramic.

The pump head 70 includes a pump bracket 71, and a cylinder 78 held within the pump bracket 71. The cylinder 78 has a cylindrical shape and fits into a cylindrical inner surface formed within the pump bracket 71. A proximal end of the pump bracket 71 is screwed with the nut 60 for preventing leakage of liquid from a gap between the pump bracket 71 and the cylinder 78. The distal end of the plunger 50 is inserted inside the cylinder 78 via the nut 60. The plunger 50 linearly reciprocates while rotating within the cylinder 78. A cylinder chamber S is defined by the distal end of the pump bracket 71, an inner side of the cylinder 78, and the distal end of the plunger 50. The internal volume of the cylinder chamber S increases or decreases in response to the linear reciprocation of the plunger 50. A cut surface, not illustrated, is provided on an outer surface of the distal side of the plunger 50 located within the cylinder 78. The cut surface with a predetermined length in the axial direction is notched in a half range in a circumferential direction. The cut surface is spaced away from the inner surface of the cylinder 78. A predetermined gap is ensured between the cut surface and the inner surface of the cylinder 78. This gap and the cylinder chamber S are communicated to each other.

A suction nozzle 73 a and an inlet nozzle 75 a are formed on one of the two sides of the pump bracket 71 that are not sandwiched by the two plate members 30. A discharge nozzle 73 b and an outlet nozzle 75 b are formed on the other side of the two sides of the pump bracket 71 that are not sandwiched by the two plate members 30. The suction nozzle 73 a and the discharge nozzle 73 b are located close to the distal side, but the inlet nozzle 75 a and the outlet nozzle 75 b are located distant from the distal side. The suction nozzle 73 a, the discharge nozzle 73 b, the inlet nozzle 75 a, and the outlet nozzle 75 b each has a flow path that is communicated to the inside of the cylinder 78 through the pump bracket 71. When the plunger 50 linearly reciprocates while rotating, the flow path of the suction nozzle 73 a and the flow path of the discharge nozzle 73 b are alternately communicated to the cylinder chamber S through the cut surface, and the volume of the cylinder chamber S increases and decreases. Thus, the liquid introduced from the suction nozzle 73 a is discharged from the discharge nozzle 73 b through the cylinder chamber S. The inlet nozzle 75 a and the outlet nozzle 75 b are provided for introducing and discharging cleaning liquid into and out of the interior.

Herein, the pump bracket 71 of the pump head 70 is made of synthetic resin. Thus, the manufacturing cost is reduced, and the weight is reduced, as compared to a case where the pump bracket 71 is made of metal. The pump bracket 71 is integrally formed with the suction nozzle 73 a, the discharge nozzle 73 b, the inlet nozzle 75 a, and the outlet nozzle 75 b. Male screwed portions are respectively formed around circumferences of the suction nozzle 73 a and the discharge nozzle 73 b. The male screwed portion of the suction nozzle 73 a is screwed with a female screwed portion of a pipe for supplying the liquid. A male screwed portion of the discharge nozzle 73 b is screwed with a female screwed portion of a pipe for discharging the liquid. The male screwed portions of the suction nozzle 73 a and the discharge nozzle 73 b are also made of synthetic resin. This reduces the manufacturing cost, as compared to, for example, a case where the above male screwed portions are made of metal. The cylinder 78 is also made of synthetic resin, but may be made of metal.

Next, the plate member 30 will be described. FIG. 5 is a view of only the plate members 30. The plate member 30 is formed into a flat plate shape, and the bending process is not performed in the plate member 30. For this reason, the manufacturing cost is reduced, compared to a plate member in which the bending process is performed. The two plate members 30 are examples of holding members, and are examples of first and second plate members.

As illustrated in FIGS. 1 and 5, the screw bolts B7 and B8 for fixing the plate member 30 to the pump bracket 71 of the pump head 70 are screwed into screw holes 37 and 38, respectively. Herein, the screw holes 37 and 38 are aligned in the axial direction of the plunger 50. Correspondingly, the screw bolt B8 is close to the distal end of the pump head 70, and the screw bolt B7 is not close thereto. In other words, the screw bolt B8 is located between the distal end and the screw bolt B7. In such a way, the two plate members 30 are held in the proximal side of the pump head 70 with the screw bolts B7, and in the distal side of the pump head 70 with the screw bolts B8. This suppresses the pump head 70 from vibrating in the proximal side and the distal side thereof in response to the driving of the plunger 50. The screw bolts B7 and B8 are examples of first and second fixing members, respectively. The first and second fixing members are not limited thereto, and may be screws.

While the exemplary embodiments of the present invention have been illustrated in detail, the present invention is not limited to the above-mentioned embodiments, and other embodiments, variations and variations may be made without departing from the scope of the present invention. 

What is claimed is:
 1. A plunger pump comprising: a motor; a bracket attached to the motor; a holding member fixed to the bracket; a plunger extending in a axial direction; a pump head holding the plunger such that the plunger is capable of rotating and reciprocating in the axial direction; and a joint mechanism for converting rotation of the motor into rotation and reciprocation of the plunger, wherein the holding member includes first and second plate members each formed into a flat plate shape, and the first and second plate members are parallel to each other so as to sandwich the pump head.
 2. The plunger pump according to claim 1, wherein the first and second plate members are fixed to the pump head by first and second fixing members, respectively, and the second fixing member is located between a distal end of the pump head and the first fixing member.
 3. The plunger pump according to claim 1, wherein the pump head includes a pump bracket made of synthetic resin.
 4. The plunger pump according to claim 3, wherein the pump bracket includes a suction nozzle and a discharge nozzle that are formed integrally with the pump bracket, and an outer surface of the suction nozzle and an outer surface of the discharge nozzle are each formed with male screw portion. 